CN112438052B

CN112438052B - Non-linear control of a loudspeaker system with a current source amplifier

Info

Publication number: CN112438052B
Application number: CN201980048165.7A
Authority: CN
Inventors: 詹姆斯·F·拉扎尔; 帕斯卡·M·布鲁内
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2018-08-07
Filing date: 2019-01-25
Publication date: 2022-07-26
Anticipated expiration: 2039-01-25
Also published as: EP3785451A4; CN112438052A; WO2020032333A1; US10542361B1; US20200053493A1; EP3785451A1

Abstract

One embodiment provides a system for nonlinear control of a loudspeaker. The system comprises: a current source amplifier connected to the microphone; and a controller connected to the current source amplifier. The controller is configured to: the method comprises determining a target displacement of a diaphragm of a loudspeaker driver based on a source signal for reproduction via a loudspeaker, determining a control current based on the target displacement of the diaphragm and a first physical model of the loudspeaker, and sending a control current signal indicative of the control current to a current source amplifier. The current source amplifier outputs the control current based on the control current signal to drive a speaker driver. The actual displacement of the diaphragm during reproduction of the source signal is controlled based on the control current via the control current signal.

Description

Non-linear control of a loudspeaker system with a current source amplifier

Technical Field

One or more embodiments relate generally to loudspeakers, and in particular, to a method and system for nonlinear control of a loudspeaker system having a current source amplifier.

Background

The loudspeakers generate sound when connected to an integrated amplifier, Television (TV) set, radio, music player, electronic sound generating device (e.g., smart phone, computer), video player, etc.

Disclosure of Invention

One embodiment provides a system for nonlinear control of a loudspeaker. The system includes a current source amplifier connected to a loudspeaker; and a controller connected to the current source amplifier. The controller is configured to: the method comprises determining a target displacement of a diaphragm of a loudspeaker driver of the loudspeaker based on a source signal for reproduction via the loudspeaker, determining a control current based on the target displacement of the diaphragm and a first physical model of the loudspeaker, and sending a control current signal indicative of the control current to a current source amplifier. The current source amplifier outputs the control current based on the control current signal to drive a speaker driver. The actual displacement of the diaphragm during reproduction of the source signal is controlled based on the control current via the control current signal.

Another embodiment provides a method for nonlinear control of a loudspeaker. The method comprises the following steps: a target displacement of a diaphragm of a speaker driver of a loudspeaker is determined based on a source signal for reproduction via the loudspeaker. The method further comprises the following steps: a control current is determined based on the target displacement of the diaphragm and a physical model of the loudspeaker, and a control current signal indicative of the control current is sent to a current source amplifier connected to the loudspeaker. The current source amplifier outputs the control current based on the control current signal to drive a speaker driver. The actual displacement of the diaphragm during reproduction of the source signal is controlled based on the control current via the control current signal.

An embodiment provides a loudspeaker device, wherein the loudspeaker device comprises: a speaker driver including a diaphragm; a current source amplifier connected to the speaker driver; and a controller connected to the current source amplifier. The controller is configured to: the method comprises determining a target displacement of a diaphragm of a loudspeaker driver based on a source signal for reproduction via a loudspeaker device, determining a control current based on the target displacement of the diaphragm and a physical model of the loudspeaker device, and sending a control current signal indicative of the control current to a current source amplifier. The current source amplifier outputs the control current based on the control current signal to drive a speaker driver. The actual displacement of the diaphragm during reproduction of the source signal is controlled based on the control current via the control current signal.

One or more embodiments relate generally to loudspeakers, and in particular, to a method and system for nonlinear control of a loudspeaker system having a current source amplifier. One embodiment provides a system for nonlinear control of a loudspeaker. The system comprises: a current source amplifier connected to the microphone; and a controller connected to the current source amplifier. The controller is configured to: the method comprises determining a target displacement of a diaphragm of a loudspeaker driver of the loudspeaker based on a source signal for reproduction via the loudspeaker, determining a control current based on the target displacement of the diaphragm and a first physical model of the loudspeaker, and sending a control current signal indicative of the control current to a current source amplifier. The current source amplifier outputs a control current based on the control current signal to drive the speaker driver. The actual displacement of the diaphragm during reproduction of said source signal is controlled based on the control current via the control current signal.

Another embodiment provides a method for nonlinear control of a loudspeaker. The method comprises the following steps: a target displacement of a diaphragm of a speaker driver of a loudspeaker is determined based on a source signal for reproduction via the loudspeaker. The method further comprises the following steps: a control current is determined based on the target displacement of the diaphragm and a physical model of the loudspeaker, and a control current signal indicative of the control current is sent to a current source amplifier connected to the loudspeaker. The current source amplifier outputs a control current based on the control current signal to drive the speaker driver. The actual displacement of the diaphragm during reproduction of the source signal is controlled via a control current signal based on a control current.

An embodiment provides a loudspeaker device, wherein the loudspeaker device comprises: a speaker driver including a diaphragm; a current source amplifier connected to the speaker driver; and a controller connected to the current source amplifier. The controller is configured to: the method comprises determining a target displacement of a diaphragm of a loudspeaker driver based on a source signal for reproduction via a loudspeaker device, determining a control current based on the target displacement of the diaphragm and a physical model of the loudspeaker device, and sending a control current signal indicative of the control current to a current source amplifier. The current source amplifier outputs a control current based on the control current signal to drive the speaker driver. The actual displacement of the diaphragm during reproduction of the source signal is controlled based on the control current via the control current signal.

Drawings

Figure 1 shows a cross-section of an example speaker driver;

fig. 2 shows an example loudspeaker device driven by a voltage source amplifier;

fig. 3 shows an example electroacoustic model for the loudspeaker device in fig. 2;

fig. 4 is an example graph illustrating non-linear characteristics of different large-signal loudspeaker parameters for the loudspeaker device in fig. 2;

FIG. 5A shows an example linear system representing a linear state space model of the loudspeaker device in FIG. 2;

FIG. 5B illustrates an example nonlinear system representing a nonlinear state space physical model of the loudspeaker device in FIG. 2;

fig. 6 illustrates an example loudspeaker control system for nonlinear control of a loudspeaker device with a current source amplifier according to an embodiment;

fig. 7 illustrates an example electroacoustic model for the loudspeaker device in fig. 6, in accordance with an embodiment;

fig. 8A illustrates an example linear system representing a linear state space model of the loudspeaker device in fig. 6, in accordance with an embodiment;

fig. 8B illustrates an example nonlinear system that represents a nonlinear state space model of the loudspeaker device in fig. 6, in accordance with an embodiment;

fig. 9 shows an example controller for the loudspeaker device in fig. 6 according to an embodiment;

fig. 10 illustrates another example controller for the loudspeaker device in fig. 6, in accordance with an embodiment;

fig. 11 is an example graph comparing a frequency response of a loudspeaker device with non-linear control to a frequency response of a different loudspeaker device without non-linear control, in accordance with an embodiment;

fig. 12A is an example graph showing the spectrum of a loudspeaker device without nonlinear control for correction of audio distortion (i.e., without anti-distortion);

fig. 12B is an example graph illustrating a spectrum of a loudspeaker device with nonlinear control for correction of audio distortion (i.e., with anti-distortion), according to an embodiment;

fig. 13 is an example flow diagram of a process for implementing nonlinear control of a loudspeaker device with a current source amplifier according to an embodiment; and

FIG. 14 is a high-level block diagram illustrating an information handling system including a computer system that may be used to implement various disclosed embodiments.

Detailed Description

These and other features, aspects, and advantages of one or more embodiments will become understood with reference to the following description, appended claims, and accompanying drawings.

The following description is made for the purpose of illustrating the general principles of one or more embodiments and is not meant to limit the inventive concepts claimed herein. Further, particular features described herein can be used in combination with other described features in each of the various possible combinations and permutations. Unless otherwise specifically defined herein, all terms are to be given their broadest possible interpretation, including meanings implied in the specification and meanings understood by those skilled in the art and/or meanings defined in dictionaries, papers, etc.

For purposes of illustration, the terms "loudspeaker," "loudspeaker device," and "loudspeaker system" may be used interchangeably in this specification.

For purposes of illustration, the terms "displacement" and "offset" may be used interchangeably in this specification.

Conventional loudspeakers are non-linear in design and produce overtones, intermodulation products and modulation noise. Non-linear audio distortion (i.e., audible distortion) compromises the sound quality (e.g., audio quality and speech intelligibility) of the audio produced by the loudspeaker. Recently, industrial design constraints have generally required loudspeaker systems to be smaller in size for portability and compactness. However, such design constraints trade sound quality for size and portability, resulting in increased audio distortion. Thus, there is a need for an anti-aliasing system for reducing/eliminating audio distortion, in particular for obtaining more pronounced/loud bass sounds from a smaller size loudspeaker system.

The loudspeaker device comprises at least one loudspeaker driver for reproducing sound. Fig. 1 shows a cross-section of an example speaker driver 55. The speaker driver 55 includes one or more moving components such as a diaphragm 56 (e.g., a conical diaphragm), a driver voice coil 57, and a former 64. The speaker driver 55 also includes one or more of the following components: (1) encircling roller 58 (e.g., a hanging roller), (2) frame 59, (3) protective cap 60 (e.g., a dome-shaped dust cap), (4) top plate 61, (5) magnet 62, (6) bottom plate 63, (7) pole piece 66, and (8) damper 67.

Typically, the loudspeaker device is driven by a voltage source amplifier. Fig. 2 shows an example loudspeaker device 40 driven by a voltage source amplifier 71. The loudspeaker device 40 comprises a loudspeaker driver 45 for reproducing sound. The microphone device 40 may be any type of microphone device such as, but not limited to, a sealed box microphone, an open box microphone, a passive radiator microphone, a microphone array, and the like. The speaker driver 45 may be any type of speaker driver such as, but not limited to, a forward speaker driver, an upward speaker driver, a downward speaker driver, and the like. The speaker driver 55 in fig. 1 is an example implementation of the speaker driver 45. The speaker driver 45 includes one or more moving components, such as a diaphragm 56 (fig. 1) and a driver voice coil 57 (fig. 1).

The voltage source amplifier 71 is connected to the loudspeaker device 40. The voltage source amplifier 71 is configured to apply a voltage U to amplify a source signal (e.g., an input audio signal) for reproduction via the speaker driver 45. The speaker driver 45 is driven by the voltage U applied from the voltage source amplifier 71.

FIG. 3 shows a circuit for driving by a voltage source amplifier 71An example electroacoustic model 70 of a moving loudspeaker device 40 (fig. 2). One or more loudspeaker parameters (i.e., loudspeaker characteristics) of the loudspeaker device 40 may be classified as one of the following domains: electrical domain or mechanical domain. In the electrical domain, examples of different loudspeaker parameters include, but are not limited to, the following: (1) a voltage U applied from the voltage source amplifier 71 for driving the speaker driver 45 of the loudspeaker device 40, (2) a resistance Re of the driver coil 57 of the speaker driver 45, (3) a current i flowing through the driver coil 57 due to the applied voltage U, (4) an inductance Le of the driver coil 57, and (5) a back electromagnetic field (EMF) generated by the movement of the driver coil 57 in the magnetic field of the motor structure of the speaker driver 45 (i.e., the driver coil 57, the top plate 61, the magnet 62, the bottom plate 63, and the pole piece 66)

Wherein the back EMF

A force factor B1 representing the motor structure and the velocity of one or more moving components of the speaker driver 45 (e.g., the diaphragm 56, the driver voice coil 57, and/or the former 64)

The product of (a) and (b).

In the mechanical domain, examples of different loudspeaker parameters include, but are not limited to, the following: (1) velocity of one or more moving components of speaker driver 45

(2) Mechanical mass M of the one or more moving components _ms (i.e., moving mass) and air load, (3) mechanical resistance R representing mechanical loss of the speaker driver 45 _ms (4) stiffness factor K of the suspension (i.e., surround roller 58, damper 67 plus air load) of the speaker driver 45 _ms And (5) a mechanical force Bl · i exerted on the one or more moving components, wherein the mechanical force Bl · i represents a force factor Bl and a flow-through drive of the motor structureThe product of the current i of actuator coil 57.

The mechanical force Bl · i is proportional to the current i flowing through the driver voice coil 57, not to the voltage U applied from the voltage source amplifier 71. The current i flowing through the driver coil 57 is affected by the nonlinear impedances Re and Le.

Fig. 4 is an example graph 150 illustrating non-linear characteristics of different large-signal loudspeaker parameters for the loudspeaker device 40 (fig. 2). The horizontal axis of the graph 150 represents the displacement in m of one or more moving components of the speaker driver 45 (e.g., the diaphragm 56 and/or the driver voice coil 57) of the loudspeaker device 40. Graph 150 includes each of the following: (1) a first curve 151 representing the change in force factor Bl in newtons per ampere (N/a), (2) a stiffness factor K in newtons per m (N/m) _ms And (3) a third curve 153 representing a change in inductance Le in millihenries (mH). As shown in fig. 4, the large-signal loudspeaker parameters vary with the displacement of the one or more moving components.

The state of the loudspeaker device 40 at each moment in time may be described using each of the following: (1) displacement x of one or more moving components of speaker driver 45, (2) velocity of one or more moving components of speaker driver 45

And (3) a current i flowing through the driver voice coil 57. Generally let X ₁ (t) indicates a vector representing the state of the loudspeaker device 40 at the sampling time t ("state vector representation"). State vector representation X ₁ (t) may be defined according to equation (1) provided below:

for purposes of illustration, the term X ₁ (t) and X ₁ May be used interchangeably in this specification.

As described in detail later below, a physical model of the loudspeaker device 40, such as a linear model (e.g., a linear state space model as shown in fig. 5A) or a non-linear model (e.g., a non-linear state space model as shown in fig. 5B), may be used to determine the estimated displacement x of the one or more moving components at the sampling time t. The physical model may be based on one or more loudspeaker parameters for the loudspeaker device 40.

Let u generally denote the input voltage for a source signal (e.g. an input audio signal) reproduced via a loudspeaker device.

Fig. 5A shows an example linear system 400 representing a linear state space model of the loudspeaker device 40. The linear system 400 may be used for representing X based on the state vector of the loudspeaker device 40 ₁ And an input voltage u for determining an estimated displacement x of one or more moving components of the speaker driver 45 (e.g. the diaphragm 56 and/or the driver voice coil 57) via the source signal reproduced by the loudspeaker device 40.

Usually make

The state vector representing the loudspeaker device 40 represents X ₁ The time derivative (i.e., the rate of change) of (i.e., "the rate of change of state vector"). Rate of change of state vector

Can be defined according to differential equation (2) provided below:

let A be ₁ 、B ₁ And C ₁ Representing a constant parameter matrix. Constant parameter matrix A ₁ 、B ₁ And C ₁ Can be expressed according to equations (3) - (5) provided below:

and

C1＝[1 0 0] (5)。

the estimated displacement x of one or more moving components of the speaker driver 45 may be calculated according to equation (6) provided below:

x＝C ₁ X ₁ (6)。

the operation of determining the estimated displacement x of one or more moving components using the linear system 400 involves performing a set of calculations based on equations (2) - (6) provided above. The linear system 400 may perform the set of calculations using one or more of the following components: (1) a first multiplication unit 401 configured to multiply by a constant parameter matrix A ₁ And state vector representation X ₁ Multiply to determine the product term A ₁ X ₁ And (2) a second multiplication unit 402 configured to multiply the constant parameter matrix B by a predetermined number of multiplication operations ₁ Multiplying by the input voltage u to determine the product term B _1u And (3) an addition unit 403 configured to add the product term a by following equation (2) provided above ₁ X ₁ And B _1u Adding to determine the rate of change of the state vector

(4) An integration unit 404 configured to determine a change rate of the state vector by changing the state vector in a time domain

Integrating to determine a state vector representation X ₁ And (5) a third multiplication unit 405 configured to multiply the constant parameter matrix C by a constant parameter matrix C according to equation (6) provided above ₁ And state vector representation X ₁ Multiplied to determine the estimated displacement x.

The system representation 400 in fig. 5A is a linear system that receives an input voltage u as an input and provides an estimated displacement x as an output.

Fig. 5B illustrates an example nonlinear system 450 representing a nonlinear state space physical model of the loudspeaker device 40. The nonlinear system 450 may be used for loudspeaker based installationsThe state vector at 40 represents X ₁ And an input voltage u for the source signal reproduced via the loudspeaker device 40 to determine an estimated displacement x of one or more moving components of the speaker driver 45 (e.g., the diaphragm 56 and/or the driver voice coil 57).

Generally let g ₁ (X ₁ U) and f ₁ (X ₁ ) Representing a state vector representation X based on loudspeaker device 40 ₁ And a non-linear function of one or more large-signal loudspeaker parameters for the loudspeaker device 40. Non-linear function g ₁ (X ₁ U) and f ₁ (X ₁ ) Can be expressed according to equations (7) - (8) provided below:

g ₁ (X ₁ ,u)＝[0 0 u/L _e (x)] ^T (7) and

usually let C ₂ Representing a constant parameter matrix. Constant parameter matrix C ₂ Can be expressed according to equation (9) provided below:

C2＝[1 0 0] (9)。

usually make

State vector representation X representing loudspeaker device 40 ₁ The time derivative (i.e., the rate of change) of (i.e., "the rate of change of the state vector"). Rate of change of state vector

Can be defined according to differential equation (10) provided below:

the estimated displacement x of one or more moving components of the speaker driver 45 may be calculated according to equation (11) provided below:

x＝C ₂ X ₁ (11)。

the operation of determining the estimated displacement x of one or more moving components using the nonlinear system 450 involves performing a set of calculations based on equations (7) - (11) provided above. The nonlinear system 450 may utilize one or more of the following components to perform the set of calculations: (1) a first calculation unit 451 configured to calculate the non-linear function f according to equation (8) provided above ₁ (X ₁ ) And (2) a second calculation unit 452 configured to calculate the non-linear function g according to equation (7) provided above ₁ (X ₁ U), (3) an addition unit 453 configured to add a non-linear function g by equation (10) provided above ₁ (X ₁ U) and f ₁ (X ₁ ) Adding to determine the rate of change of the state vector

(4) An integration unit 454 configured to perform a state vector change by changing a state vector in a time domain

Integrating to determine a state vector representation X ₁ And (5) a multiplication unit 455 configured to multiply the constant parameter matrix C by a constant parameter matrix C according to equation (11) provided above ₂ And state vector representation X ₁ Multiplied to determine the estimated displacement x.

The system representation 450 in fig. 5B is a nonlinear system that receives an input voltage u as an input and provides an estimated displacement x as an output.

In contrast to conventional loudspeakers, one or more embodiments provide a system for nonlinear control of loudspeaker devices with a current source amplifier ("nonlinear control system"). The nonlinear control system is configured to improve sound quality of the loudspeaker device by reducing audio distortion. In one embodiment, the nonlinear control system provides correction for nonlinear audio distortion by pre-distorting current to a speaker driver of a loudspeaker device. The nonlinear control system provides improved performance in terms of nonlinear audio distortion, bass extension, displacement control and loudspeaker protection.

The nonlinear control system is configured to increase or maximize bass output of the loudspeaker device by controlling motion of one or more moving components of the speaker driver (e.g., the diaphragm and/or the driver voice coil). In one embodiment, the non-linear control system enables linearization of the loudspeaker device by providing non-linear control of the motion of the one or more moving components. This allows for an increased/maximized bass extension, thereby enhancing the bass output of the loudspeaker device. The non-linear control system provides better protection of the loudspeaker device by preventing excessive displacement of the one or more moving components and overheating of the loudspeaker device.

Fig. 6 illustrates an example loudspeaker system 100 according to an embodiment. The loudspeaker system 100 is an example non-linear control system for a loudspeaker device with a current source amplifier. In particular, the loudspeaker system 100 comprises a loudspeaker device 60, wherein said loudspeaker device 60 comprises a speaker driver 65 for reproducing sound. The microphone device 60 may be any type of microphone device such as, but not limited to, a sealed box microphone, an open box microphone, a passive radiator microphone, a microphone array, and the like. The speaker driver 65 may be any type of speaker driver such as, but not limited to, a forward speaker driver, an upward speaker driver, a downward speaker driver, and the like. The speaker driver 55 in fig. 1 is an example implementation of the speaker driver 65. The speaker driver 65 includes one or more moving components, such as the diaphragm 56 (fig. 1) and the driver voice coil 57 (fig. 1).

The loudspeaker system 100 comprises a controller 110, wherein the controller 110 is configured to receive a source signal (e.g. an input audio signal) from the input source 10 for reproduction via the loudspeaker device 60. In one embodiment, the controller 110 is configured to receive source signals from different types of input sources 10. Examples of different types of input sources 10 include, but are not limited to, a mobile electronic device (e.g., a smart phone, laptop, tablet, etc.), a content playback device (e.g., a television, radio, computer, music player such as a CD player, video player such as a DVD player, turntable, etc.), or an audio receiver, etc.

Let p generally denote the target (i.e. desired) sound pressure delivered by the loudspeaker device 60 during reproduction of the source signal. As described in detail later herein, the controller 110 is configured to determine one or more of the following based on a physical model of the loudspeaker device 60 and a target sound pressure p at the sampling time t: (1) a target displacement (e.g., a target cone displacement) x of one or more moving components at a sampling time t, and (2) a target current i that produces the target displacement x at the sampling time t. For purposes of illustration, the terms "target current" and "control current" may be used interchangeably in this specification. The controller 110 is configured to generate and send a control current signal s indicative of the determined target current i to the current source amplifier 81 of the loudspeaker system 100. The control current signal s may be any type of signal such as, but not limited to, a current, a voltage, a digital signal, an analog signal, and the like.

The physical model of the loudspeaker device 60 may be based on one or more loudspeaker parameters for the loudspeaker device 60. In one embodiment, the physical model of the loudspeaker device 60 utilized by the controller 110 is a linear model (e.g., a linear state space model as shown in fig. 8A). In another embodiment, the physical model of the loudspeaker device 60 utilized by the controller 110 is a non-linear model (e.g., a non-linear state space model as shown in fig. 8B).

As shown in fig. 6, the current source amplifier 81 is connected to the microphone arrangement 60 and the controller 110. The current source amplifier 81 is a power amplifier, wherein the power amplifier is configured to output (i.e., apply or generate) an actual current (i.e., an applied current) i for each sampling time t based on a control current signal s received from the controller 110, wherein the control current signal s is indicative of a target current i determined by the controller 110 at the sampling time t. The control current signal s controls the current source amplifier 81, and triggers the current source amplifier 81 to output substantially the same amount of current as the target current i to amplify the source signal at the sampling time t. The loudspeaker driver 65 is driven by the actual current i output by the current source amplifier 81 to control the actual displacement of one or more moving components during reproduction of the source signal. In particular, the loudspeaker system 100 controls the cone displacement/motion of one or more moving components by performing current corrections based on the target current i, resulting in a target sound wave having a target sound pressure p at the sampling time t. The target current i limits an actual displacement (e.g., an actual conical displacement) of the one or more moving components to within a predetermined range of safe displacements.

The loudspeaker system 100 facilitates a higher level of audio reproduction with improved sound quality and additional control and protection of the loudspeaker device 60.

As described in detail later herein, the controller 110 is configured to: audio distortion is addressed during reproduction of the source signal via the speaker driver 65 by recalculating a target current i required to generate a target sound pressure p at each instant/sample time t based on the instantaneous position of one or more moving components, wherein the actual current i output by the current source amplifier 81 is based on the target current i.

In one embodiment, the loudspeaker system 100 may be integrated in different types of electrodynamic transducers with a wide range of applications, such as, but not limited to, the following: computers, Televisions (TVs), smart devices (e.g., smart TVs, smart phones, etc.), sound bars, subwoofers, wireless and portable speakers, mobile phones, automotive speakers, and the like.

In contrast to conventional systems that utilize a voltage source amplifier (e.g., the loudspeaker device 40 driven by the voltage source amplifier 71 in fig. 2), the loudspeaker system 100 utilizes a current source amplifier to achieve nonlinear control of the loudspeaker device 60. As described in detail later herein, the loudspeaker system 100 is a simplified non-linear control system that reduces demand and cost. For example, the loudspeaker system 100 may require about half the Digital Signal Processing (DSP) requirements of conventional systems and have a lower cost.

Fig. 7 shows an example electroacoustic model 80 for a loudspeaker device 60 according to an embodiment. For one or more of the loudspeaker devices 60The loudspeaker parameters (i.e., loudspeaker characteristics) may be classified into one of the following domains: electrical domain or mechanical domain. In the electrical domain, examples of different loudspeaker parameters include, but are not limited to, the following: (1) the actual current i output by the current source amplifier 81 for driving the speaker driver 65 of the loudspeaker device 60, (2) the resistance re (t) of the driver coil 57 of the speaker driver 65, (3) the inductance le (x) of the driver coil 57, and (4) the back EMF generated by the movement of the driver coil 57 in the magnetic field of the motor structure of the speaker driver 65 (i.e., the driver coil 57, the top plate 61, the magnet 62, the bottom plate 63, and the pole piece 66)

Wherein the back EMF

A force factor B1 representing the motor configuration and the velocity of one or more moving components of the speaker driver 65 (e.g., the diaphragm 56, the driver coil 57, and/or the former 64)

The product of (a).

In the mechanical domain, examples of different loudspeaker parameters include, but are not limited to, the following: (1) velocity of one or more moving components of speaker driver 65

(2) Mechanical mass M of the one or more moving components _ms (i.e., moving mass) and air load, and (3) resistance R representing mechanical loss of the speaker driver 65 _ms

(4) Stiffness factor K of the suspension (i.e., surround roller 58, damper 67 plus air load) of speaker driver 65 _ms (x) And (5) a mechanical force bl (x) i exerted on the one or more moving components, wherein mechanical force bl (x) i represents a force factor bl (x) of driver voice coil 57 and a real output from current source amplifier 81Product of the actual currents i.

Unlike a loudspeaker device (e.g., loudspeaker device 40 in fig. 2) driven by a voltage source amplifier, the nonlinear impedance R _e (T) and L _e (x) There is no effect on the mechanical force bl (x) i exerted on one or more moving components of the speaker driver 65, since the actual current i output by the current source amplifier 81 is independent of the non-linear impedance R _e (T) and L _e (x) And flows. Since the actual current i output by the current source amplifier 81 flows independently of the non-linear impedances, the controller 110 of the loudspeaker system 100 does not need to take these non-linear impedances into account when performing the calculations, thereby simplifying the calculations performed. As a result of the simplified calculations, the loudspeaker system 100 may require about half the DSP requirements of conventional systems and have a lower cost.

The state of the loudspeaker device 60 at each moment in time may be described using each of the following: (1) target displacement x of one or more moving components of the speaker driver 65, and (2) velocity of one or more moving components of the speaker driver 65

Usually let X ₂ (t) indicates a vector representing the state of the loudspeaker device 60 at the sampling time t ("state vector representation"). In one embodiment, the state vector represents X ₂ (t) may be defined according to equation (12) provided below:

for purposes of this specification, the term X ₂ (t) and X ₂ Are used interchangeably in this specification.

Fig. 8A illustrates an example linear system 410 representing a linear state space model of the loudspeaker device 60 according to an embodiment. The linear system 410 may be used to represent X based on the state vector of the loudspeaker device 60 ₂ And a current i output from the current source amplifier 81 for driving the speaker driver 65An estimated displacement x of one or more moving components of the speaker driver 65 (e.g., the diaphragm 56 and/or the driver voice coil 57) is determined.

Usually let A be ₂ 、B ₂ And C ₃ Representing a constant parameter matrix. In one embodiment, the constant parameter matrix A ₂ 、B ₂ And C ₃ Can be expressed according to equations (13) - (15) provided below:

and

C ₃ ＝[ 1 0] (15)。

usually make

State vector representation X representing loudspeaker device 60 ₂ The time derivative (i.e., the rate of change) of (i.e., "the rate of change of state vector"). In one embodiment, the rate of change of the state vector may be defined in accordance with differential equation (16) provided below

In one embodiment, the estimated displacement x of one or more moving components may be calculated according to equation (17) provided below:

x＝C ₃ X ₂ (17)。

in one embodiment, the controller 110 of the loudspeaker system 100 is configured to recursively determine an estimated displacement x of one or more moving components using the linear system 410. The operation of recursively determining an estimated displacement x of one or more moving components using linear system 410 involvesA set of recursive calculations based on equations (13) - (17) provided above are performed. In an example embodiment, the controller 110 includes one or more of the following components: (1) a first multiplying unit 411 configured to multiply by a constant parameter matrix A ₂ And state vector representation X ₂ Multiplying to determine a product term A ₂ X ₂ And (2) a second multiplication unit 412 configured to multiply the constant parameter matrix B by a predetermined number of multiplication operations ₂ Multiplying by the current i to determine the product term B _2i (3) an adding unit 413 configured to add the product term a by the equation (16) provided above ₂ X ₂ And B _2i Adding to determine the rate of change of the state vector

(4) An integration unit 414 configured to perform a state vector transformation by varying the rate of change of the state vector in the time domain

Integrating to determine a state vector representation X ₂ And (5) a third multiplication unit 415 configured to multiply the constant parameter matrix C by a constant parameter matrix C according to equation (17) provided above ₃ And state vector representation X ₂ Multiplied to determine the estimated displacement x.

As shown in fig. 8A, the system 410 is a linear system that receives current i as an input and provides an estimated displacement x as an output. Utilizing linear system 410 provides a reduced system order for system transfer function simplification compared to linear system 400 in fig. 5A. Since the current i is independent of the non-linear impedance R _e (T) and L _e (x) While flowing (i.e., without R) _e (T) and L _e (x) Dependent) so the current source amplifier 81 provides an output with a high impedance (i.e., i), and the system transfer function is not affected by changes in the non-linear impedance, thereby eliminating the need to optimize such non-linear impedance. Thus, the non-linear control of the loudspeaker device 60 and the calculations performed by the controller 110 are simplified by the linear system 410. As a result, loudspeaker system 100 may require about half the DSP requirements of conventional systems and have a lower cost.

Fig. 8B illustrates an example nonlinear system 460 representing a nonlinear state space model of the loudspeaker device 60, in accordance with an embodiment. The non-linear system 460 may be used to represent X based on the state vector of the loudspeaker device 60 ₂ And the current i output by the current source amplifier 81 for driving the speaker driver 65 to determine an estimated displacement x of one or more moving components of the speaker driver 65 (e.g., the diaphragm 56 and/or the driver voice coil 57).

Generally let g ₂ (X ₂ I) and f ₂ (X ₂ ) Representing a state vector representation X based on a loudspeaker device 60 ₂ And a non-linear function of one or more large-signal loudspeaker parameters for the loudspeaker device 60. In one embodiment, the non-linear function g ₂ (X ₂ I) and f ₂ (X ₂ ) Expressed according to equations (18) - (19) provided below:

g ₂ (X ₂ ,i*)＝[0 Bl(x)·i*/M _ms ] ^T (18) and an

Usually let C ₄ Representing a constant parameter matrix. In one embodiment, the constant parameter matrix C ₄ Can be expressed according to equation (20) provided below:

C ₄ ＝[1 0] (20)。

usually make

State vector representation X representing loudspeaker device 60 ₂ The time derivative (i.e., the rate of change) of (i.e., "the rate of change of the state vector"). In one embodiment, the rate of change of the state vector may be defined in accordance with differential equation (21) provided below

In one embodiment, the estimated displacement x of one or more moving components of the speaker driver 65 may be calculated according to equation (22) provided below:

x＝C ₄ X ₂ (22)。

in one embodiment, the controller 110 of the loudspeaker system 100 is configured to recursively determine an estimated displacement x of one or more moving components of the speaker driver 65 using the non-linear system 460. The operation of recursively determining the estimated displacement x of one or more moving components using the nonlinear system 460 involves performing a set of recursive calculations based on equations (18) - (22) provided above. The non-linear system 460 may utilize one or more of the following components to perform the set of calculations: (1) a first calculation unit 461 configured to calculate the non-linear function f according to equation (19) provided above ₂ (X ₂ ) (2) a second calculation unit 462 configured to calculate the non-linear function g according to equation (18) provided above ₂ (X ₂ I), (3) an adding unit 463 configured to add a non-linear function g by applying the non-linear function g according to equation (21) provided above ₂ (X ₂ I) and f ₂ (X ₂ ) Adding to determine the rate of change of the state vector

(4) An integration unit 464 configured to determine a state vector change rate by varying the state vector in a time domain

Integrating to determine a state vector representation X ₂ And (5) a multiplication unit 465 configured to multiply the constant parameter matrix C by a constant parameter matrix C according to equation (22) provided above ₄ And state vector representation X ₂ Multiplied to determine the estimated displacement x.

As shown in fig. 8B, the system 460 is a nonlinear system that receives current i as an input and provides an estimated displacement x as an output. Utilizing a non-linear system 460 provides system transfer function simplification as compared to linear system 450 in FIG. 5BReduced system order. Since the current i is independent of the non-linear impedance R _e (T) and L _e (x) While flowing (i.e., without R) _e (T) and L _e (x) Dependent) so the current source amplifier 81 provides an output with a high impedance (i.e., i), and the system transfer function is not affected by changes in the non-linear impedance, thereby eliminating the need to optimize such non-linear impedance. Thus, the control of the loudspeaker device 60 and the calculations performed by the controller 110 are simplified by the non-linear system 460. As a result, loudspeaker system 100 may require about half the DSP requirements of conventional systems and have a lower cost.

Fig. 9 illustrates an example controller 200 for a loudspeaker device 60 according to an embodiment. In one embodiment, the controller 110 of the loudspeaker system 100 is the controller 200. In one embodiment, the controller 200 comprises a trajectory planning unit 210, wherein the trajectory planning unit 210 is configured to: a target displacement (i.e., target cone displacement) x of one or more moving components of the speaker driver 65 (e.g., the diaphragm 56 and/or the driver voice coil 57) at each sampling time t is determined based on a physical model of the loudspeaker device 60 and a target sound pressure p delivered at the sampling time t for the loudspeaker device 60 during reproduction of the source signal (e.g., the input audio signal). In one embodiment, the loudspeaker system 100 is configured to determine a target sound pressure p from the source signal.

In one embodiment, the trajectory planning unit 210 utilizes a linear model (e.g., the linear state space model 410 in fig. 8A) to determine the target displacement x of the one or more moving components, thereby implementing trajectory planning that includes linear processing of the source signals. In another embodiment, the trajectory planning unit 210 determines the target displacement x of the one or more moving components using a non-linear model (e.g., the non-linear state space model 460 in fig. 8B).

In one embodiment, the controller 200 comprises a flatness-based feedforward control unit 220, wherein the flatness-based feedforward control unit 220 implements a feedforward control to determine the control current i for each sampling time t. Specifically, the flatness-based feedforward control unit 220 is configured to: the control current i is determined based on the target displacement x for the sampling time t received from the trajectory planning unit 210 and another physical model (e.g. a non-linear model) of the loudspeaker device 60 to drive the loudspeaker driver 65 to produce the target displacement x.

In one embodiment, the flatness-based feedforward control unit 220 is configured to: the control current i at the sampling time t is determined based on a non-linear model of the loudspeaker device 60. For example, in one embodiment, if the loudspeaker device 60 is a sealed-box speaker, the flatness-based feedforward control unit 220 may determine the control current i at the sampling time t according to a single equation (23) provided below:

wherein the content of the first and second substances,

is a target velocity (e.g., target cone velocity) of one or more moving components of the speaker driver 65,

is a target acceleration (e.g., target cone acceleration), K, of the one or more moving components _ms (x) is the stiffness factor of the suspension of the loudspeaker driver 65 (i.e. surround roller 58, bounce 67 plus air load) based on the target displacement x, R _ms

Is based on target speed

And Bl (x) is the force factor of the driver voice coil 57 of the speaker driver 65 based on the target displacement x. The flatness-based feedforward control unit 220 is configured to generate and send a control current signal s indicative of the determined control current i toThe current source amplifier 81 of the loudspeaker system 100. The control current signal s may be any type of signal such as, but not limited to, a current, a voltage, a digital signal, an analog signal, and the like.

The current source amplifier 81 of the loudspeaker system 100 is configured to: the actual current (i.e., the applied current) i is output (i.e., applied or generated) for each sampling time t based on a control current signal s received from the flatness-based feedforward control unit 220, where the control current signal s is indicative of the control current i determined by the flatness-based feedforward control unit 220 at the sampling time t. The control current signal s controls the current source amplifier 81, and triggers the current source amplifier 81 to output substantially the same amount of current as the control current i to amplify the source signal at the sampling time t. The speaker driver 65 is driven by the actual current i from the current source amplifier 81, thereby controlling the actual displacement (i.e. the actual conical displacement) of one or more moving components of the speaker driver 65 during reproduction of the source signal and resulting in the generation of sound waves with an actual sound pressure p.

Fig. 10 illustrates an example controller 250 for the loudspeaker device 60 according to an embodiment. In one embodiment, the controller 110 of the loudspeaker system 100 is the controller 250. In one embodiment, the controller 250 comprises a trajectory planning unit 260, wherein the trajectory planning unit 260 is configured to: a target displacement (i.e., target cone displacement) x of one or more moving components of the speaker driver 65 (e.g., the diaphragm 56 and/or the driver voice coil 57) at each sampling time t is determined based on a physical model of the loudspeaker device 60 and a target sound pressure p delivered by the loudspeaker device 60 at the sampling time t during reproduction of the source signal (e.g., the input audio signal). In one embodiment, the loudspeaker system 100 is configured to determine a target sound pressure p from the source signal.

In one embodiment, the trajectory planning unit 260 utilizes a linear model (e.g., the linear state space model 410 in fig. 8A) to determine the target displacement x of one or more moving components, thereby implementing trajectory planning that includes linear processing of the source signals. In another embodiment, the trajectory planning unit 260 utilizes a non-linear model (e.g., the non-linear state space model 460 in fig. 8B) to determine the target displacement x of the one or more moving components.

In one embodiment, the controller 250 comprises a flatness-based feed forward control unit 270, wherein said feed forward control unit 270 implements feed forward control to determine the control current i for each sampling time t. Specifically, the flatness-based feedforward control unit 270 is configured to: the control current i is determined based on the target displacement x for the sampling time t received from the trajectory planning unit 260 and the physical model of the loudspeaker device 60 to drive the loudspeaker driver 65 to produce the target displacement x.

In one embodiment, the flatness-based feedforward control unit 270 is configured to: the control current i at the sampling time t is determined based on a non-linear model of the loudspeaker device 60. For example, in one embodiment, if the loudspeaker device 60 is a sealed box loudspeaker, the flatness-based feedforward control unit 270 may determine the control current i at the sampling time t according to the single equation (23) provided above. The flatness-based feedforward control unit 270 is configured to: a control current signal s indicative of the determined control current i is generated and sent to the current source amplifier 81 of the loudspeaker system 100. The control current signal s may be any type of signal such as, but not limited to, a current, a voltage, a digital signal, an analog signal, and the like.

The current source amplifier 81 of the loudspeaker system 100 is configured to: the actual current (i.e., the applied current) i is output (i.e., applied or generated) for each sampling time t based on a control current signal s received from the flatness-based feedforward control unit 270, where the control current signal s is indicative of the control current i determined by the flatness-based feedforward control unit 270 at the sampling time t. The control current signal s controls the current source amplifier 81, and triggers the current source amplifier 81 to output substantially the same amount of current as the control current i to amplify the source signal at the sampling time t. The speaker driver 65 is driven by the actual current i from the current source amplifier 81, thereby controlling the actual displacement (i.e., the actual cone displacement) of one or more moving components of the speaker driver 65 during reproduction of the source signal and resulting in the generation of a sound wave having the actual sound pressure p at the sampling time t.

The controller 250 is configured to: the voltage v driving the speaker driver 65 is monitored at each sampling time t, and a prediction error for correcting the feedforward control implemented by the flatness-based feedforward control unit 270 is determined based on the comparison between the measured voltage v and the calculated control voltage v x for the sampling time t. In one embodiment, the flatness-based feedforward control unit 270 is further configured to: a control voltage v is determined for each sampling time t to produce a target displacement x at the sampling time t. For example, in one embodiment, if the loudspeaker device 60 is a sealed box loudspeaker, the flatness-based feedforward control unit 270 may determine the control voltage v at the sampling time t according to equation (24) provided below:

wherein Bl (x) is a force factor, and L _e (x) is the inductance of the driver voice coil 57 based on the target displacement x at the sampling time t.

At each sampling time t, the controller 250 measures the voltage v at the power terminals of the speaker driver 65 in response to the actual current i from the current source amplifier 81. In an embodiment, the controller 250 comprises a comparison unit 290, wherein the comparison unit 290 is configured to determine a voltage error Δ v representing a difference between the voltage v and the control voltage v for the sampling time t.

The controller 250 further comprises a feedback control unit 280, wherein the feedback control unit 280 is configured to: one or more loudspeaker model parameters for the loudspeaker device 60 are generated based on the voltage error av, wherein the one or more loudspeaker model parameters comprise a prediction error for correcting a feedforward control implemented by the flatness-based feedforward control unit 270. The loudspeaker model parameters are tuned to more closely fit the measured data. For example, the loudspeaker model parameters may be adjusted to compensate for variations resulting from intrinsic and extrinsic variations, such as manufacturing tolerances, current operating conditions (e.g., temperature of the driver voice coil 57), environmental effects (such as pressure and temperature), and aging of components and materials of the loudspeaker system 100. Accordingly, the loudspeaker system 100 may account for changes in components and materials over time and environmental conditions and account for adverse effects of temperature (e.g., changes in resistance of the driver voice coil 57), pressure, and aging.

Based on the generated loudspeaker model parameters, any resulting corrections (e.g., current corrections) performed may compensate for one or more inaccuracies (e.g., manufacturing dispersion) and/or audio drift (e.g., resulting from overheating of the loudspeaker device 60) associated with the physical model utilized by the controller 250. Prediction error may be used to minimize the inaccuracy.

For example, in one embodiment, the prediction error may be used to calculate a correction to the control current i (i.e., a current correction), thereby improving the accuracy of the loudspeaker system 100 and the quality of the audio output reproduced by the loudspeaker device 60.

The feedback control implemented by the flatness-based feedforward control unit 270 may be based on various control methods such as, but not limited to, state feedback control, adaptive control (e.g., using online system identification), proportional-integral-derivative (PID) control, and the like.

In another embodiment, if the speaker driver 65 has well-known and stable characteristics, the flatness-based feedforward control unit 270 need not account for any prediction error, thereby eliminating the need for a feedback control unit 280 and a comparison unit 290 (e.g., similar to the controller 200 in fig. 9).

Fig. 11 is an example graph 500 comparing a frequency response of a loudspeaker device with non-linear control to a frequency response of a different loudspeaker device without non-linear control, in accordance with an embodiment. The horizontal axis of the graph 500 represents frequency in Hz. The vertical axis of the graph 500 represents the sound pressure level in dB. The graph 500 includes a first curve 501 and a second curve 502, where the first curve 501 represents the frequency response of a first loudspeaker device without non-linear control and the second curve 502 represents the frequency response of a second loudspeaker device with non-linear control (e.g., implemented using the loudspeaker system 100).

If the first loudspeaker device is integrated with one or more components of the loudspeaker system 100 (e.g., the controller 200 or the controller 250), the loudspeaker system 100 may extend the roll-off of the frequency response of the first loudspeaker device at bass frequencies while maintaining bass distortion and ensuring that the displacement of one or more moving components of the first loudspeaker device (e.g., the diaphragm and/or the driver voice coil) is within a safe range of operation. As indicated by the directional arrows shown in fig. 11, loudspeaker system 100 provides a system that can achieve bass extension (i.e., deeper, louder bass) with lower audio distortion.

Fig. 12A is an example graph 510 showing the spectrum of a loudspeaker device without nonlinear control for correction of audio distortion (i.e., without anti-distortion). The horizontal axis of graph 510 represents frequency in Hz. The vertical axis of the graph 510 represents the sound pressure level in dB. As shown in fig. 12A, the effect of the nonlinear impedance on the loudspeaker device may generate intermodulation products, thereby increasing audio distortion.

Fig. 12B is an example graph 520 illustrating a spectrum of a loudspeaker device with nonlinear control for correction of audio distortion (i.e., with anti-distortion), according to an embodiment. The loudspeaker device may be integrated with one or more components of the loudspeaker system 100 (e.g., the controller 200 or the controller 250). The horizontal axis of graph 520 represents frequency in Hz. The vertical axis of the graph 520 represents the sound pressure level in dB. Compared to graph 510 in fig. 12A, the effect of the nonlinear impedance on the loudspeaker device is cancelled, as shown in fig. 12B, thereby reducing intermodulation products and thus audio distortion.

Fig. 13 is an example flow diagram of a process 700 for implementing nonlinear control of a loudspeaker device with a current source amplifier, according to an embodiment. Processing block 701 includes receiving a source signal for reproduction via a loudspeaker device (e.g., loudspeaker device 60). Processing block 702 includes determining a target displacement of one or more moving components of a speaker driver (e.g., diaphragm 56 and/or driver voice coil 57) of the loudspeaker device based on the source signal and a first physical model of the loudspeaker device (e.g., the linear state space model in fig. 8A). Processing block 703 includes determining the control current based on the target displacement and a second physical model of the loudspeaker device (e.g., the non-linear state space model in fig. 8B). Processing block 704 includes sending a control current signal indicative of the control current to a current source amplifier connected to the loudspeaker device, wherein the current source amplifier outputs the control current based on the control current signal to drive the speaker driver, and wherein an actual displacement of the one or more moving components during reproduction of the source signal is controlled based on the control current via the control current signal.

In one embodiment, one or more components of the loudspeaker system 100 (such as the controller 200 or the controller 250) are configured to perform processing blocks 701-704.

FIG. 14 is a high-level block diagram illustrating an information handling system including a computer system 600 that may be used to implement various disclosed embodiments. Computer system 600 includes one or more processors 601, and may also include an electronic display device 602 (for displaying video, graphics, text, and other data), a main memory 603 (e.g., Random Access Memory (RAM)), a storage device 604 (e.g., a hard disk drive), a removable storage device 605 (e.g., a removable storage drive, a removable memory module, a tape drive, an optical drive, a computer readable medium having computer software and/or data stored thereon), a user interface device 606 (e.g., a keyboard, a touch screen, keys, a pointing device), and a communication interface 607 (e.g., a modem, a network interface (such as an ethernet card), a communication port, or a PCMCIA slot and card).

Communications interface 607 allows software and data to be transferred between computer system 600 and external devices. The nonlinear controller also includes a communication infrastructure 608 (e.g., a communication bus, cross-over bar, or network) to which the above-described devices/modules 601-607 are connected.

Information communicated via communications interface 607 may be in the form of signals, such as electronic, electromagnetic, optical, or other signals capable of being received by communications interface 607 via a communications link, which carries signals and may be implemented using wire or cable, fiber optics, a phone line, a cellular phone link, a Radio Frequency (RF) link, and/or other communications channels. The computer program instructions which represent block diagrams and/or flowchart diagrams herein may be loaded onto a computer, programmable data processing apparatus, or processing device to cause a series of operations to be performed thereon to produce a computer implemented process. In one embodiment, the processing instructions for process 700 (fig. 13) may be stored as program instructions on memory 603, storage 604, and/or removable storage 605 for execution by processor 601.

Embodiments have been described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products. In some cases, each block of such diagrams/figures, or combinations thereof, may be implemented by computer program instructions. The computer program instructions, when provided to a processor, produce a machine, such that the instructions, which execute via the processor, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. Each block in the flow charts/block diagrams may represent hardware and/or software modules or logic. In alternative implementations, the functions noted in the block may occur out of the order noted in the figures, may occur concurrently, and so on.

The terms "computer program medium," "computer usable medium," "computer readable medium," and "computer program product" are used to generally refer to media such as main memory, secondary memory, removable storage drive, a hard disk installed in a hard disk drive, and signals. These computer program products are means for providing software to a computer system. The computer readable medium allows a computer system to read data, instructions, messages or message packets, and other computer readable information from the computer readable medium. The computer readable medium may include, for example, non-volatile memory, such as floppy disks, ROM, flash memory, disk drive memory, CD-ROM, and other permanent storage. This is useful, for example, for transferring information (such as data and computer instructions) between computer systems. The computer program instructions may be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.

As will be appreciated by one skilled in the art, aspects of the embodiments may be embodied as a system, method or computer program product. Accordingly, aspects of the embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a "circuit," module "or" system. Furthermore, aspects of the embodiments may take the form of a computer program product embodied in one or more computer-readable media having computer-readable program code embodied therein.

Any combination of one or more computer-readable media may be utilized. The computer-readable medium may be a computer-readable storage medium (e.g., a non-transitory computer-readable storage medium). A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

Computer program code for carrying out operations for aspects of one or more embodiments may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider).

In some cases, aspects of one or more embodiments are described above with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products. In some cases, it will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a special purpose computer or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

Reference in the claims to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more. All structural and functional equivalents to the elements of the above-described exemplary embodiments that are currently known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the present claims.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising …, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the embodiments has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the embodiments in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention.

Although the embodiments have been described with reference to specific versions thereof; however, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.

Claims

1. A system for nonlinear control of a loudspeaker, the system comprising:

a current source amplifier connected to the microphone; and

a controller connected to the current source amplifier, wherein the controller is configured to:

determining a target displacement of a diaphragm of a speaker driver of a loudspeaker based on a source signal for reproduction via the loudspeaker;

determining a control current based on a target displacement of the diaphragm and a first physical model of the loudspeaker, wherein the first physical model relating the displacement of the diaphragm to the control current has a value defined as

Is represented or defined as a three-dimensional state vector

Where x is the displacement of the diaphragm,

is the velocity of the diaphragm, i is the control current; and is provided with

A control current signal indicative of the control current is sent to a current source amplifier,

wherein the current source amplifier outputs the control current based on the control current signal to drive the loudspeaker driver, and wherein the actual displacement of the diaphragm during reproduction of the source signal is controlled via the control current signal based on the control current.

2. The system of claim 1, wherein the first physical model is a non-linear model.

3. The system of claim 1, wherein the controller is configured to: a target displacement of the diaphragm is determined based on a target sound pressure delivered by the system during reproduction of the source signal and a second physical model of the loudspeaker.

4. The system of claim 3, wherein the second physical model is a linear model.

5. The system of claim 3, wherein the second physical model is a non-linear model.

6. The system of claim 1, wherein the controller is further configured to:

determining a control voltage based on the target displacement of the diaphragm and the first physical model;

monitoring an actual voltage measured at a power terminal of a speaker driver during reproduction of the source signal; and is

A prediction error is generated based on a comparison of the control voltage and the actual voltage.

7. The system of claim 6, wherein the controller is further configured to:

one or more loudspeaker parameters of the first physical model are adjusted based on the prediction error.

8. The system of claim 1 wherein the control current limits the actual displacement of the diaphragm to a predetermined range of safe displacement and increases low frequency bass output.

9. The system of claim 1, wherein the current source amplifier is configured to: driving a speaker driver by amplifying the source signal based on the control current.

10. The system of claim 1, wherein a system transfer function of the system is independent of one or more of the following nonlinear impedances: the resistance of the driver voice coil of the speaker driver or the inductance of the driver voice coil.

11. The system of claim 1, wherein the mechanical force exerted on the diaphragm is based on an actual current output by a current source amplifier, wherein the actual current is based on the control current and the actual current is independent of one or more of the following nonlinear impedances: the resistance of the driver voice coil of the speaker driver or the inductance of the driver voice coil.

12. A method for nonlinear control of a loudspeaker, the method comprising:

determining a control current based on a target displacement of the diaphragm and a physical model of the loudspeaker, wherein the physical model relating the displacement of the diaphragm to the control current has a value defined as

Is represented or defined as a three-dimensional state vector

Of a two-dimensional state vector ofA state space model, where x is the displacement of the diaphragm,

Sending a control current signal indicative of the control current to a current source amplifier connected to the loudspeaker, wherein the current source amplifier outputs the control current based on the control current signal to drive the loudspeaker driver, and wherein the actual displacement of the diaphragm during reproduction of the source signal is controlled based on the control current via the control current signal.

13. The method of claim 12, wherein the physical model is a non-linear model.

14. The method of claim 12, wherein the method further comprises:

determining a control voltage based on a target displacement of the diaphragm and the physical model;

monitoring an actual voltage measured at a power terminal of a speaker driver during reproduction of the source signal;

generating a prediction error based on a comparison of the control voltage and the actual voltage; and is provided with

Adjusting one or more loudspeaker parameters of the physical model based on the prediction error.

15. The method of claim 12, wherein the control current limits the actual displacement of the diaphragm to a predetermined range of safe displacement and increases low frequency bass output.

16. The method of claim 12, wherein the mechanical force exerted on the diaphragm is based on an actual current output by a current source amplifier, wherein the actual current is based on the control current, and the actual current is independent of one or more of the following nonlinear impedances: the resistance of the driver voice coil of the speaker driver or the inductance of the driver voice coil.

17. A loudspeaker device comprising:

a speaker driver including a diaphragm;

a current source amplifier connected to the speaker driver; and

determining a target displacement of a diaphragm of a loudspeaker driver based on a source signal for reproduction via a loudspeaker device;

determining a control current based on a target displacement of the diaphragm and a physical model of the loudspeaker device, wherein the physical model relating the displacement of the diaphragm to the control current has a value defined as

Is represented or defined as a three-dimensional state vector

Where x is the displacement of the diaphragm,

is the speed of the diaphragm, i is the control current; and is provided with

18. The loudspeaker device as recited in claim 17 wherein the physical model is a non-linear model.

19. The loudspeaker device as recited in claim 17 wherein the controller is further configured to:

generating a prediction error based on a comparison of the control voltage and the actual voltage; and is

20. The loudspeaker device as recited in claim 17 wherein:

the control current limits the actual displacement of the diaphragm to a predetermined range of safe displacement and increases the bass output at low frequencies; and is provided with

The mechanical force exerted on the diaphragm is based on an actual current output by a current source amplifier, wherein the actual current is based on the control current and the actual current is independent of one or more of the following non-linear impedances: the resistance of the driver voice coil of the speaker driver or the inductance of the driver voice coil.